package org.scboy.coobi.utils;

import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;

import cn.hutool.core.io.IoUtil;

/**
 * 文件工具类
 * @author yanghao
 *
 */
public class FileUtil {

	/**
	 * 获取文件编码
	 * @param inputStream
	 * @return
	 * @throws IOException
	 */
	public static String get_charset(InputStream inputStream) throws IOException {
		String charset = "GBK";
		byte[] first3Bytes = new byte[3];
		BufferedInputStream bis = null;
		try {
			boolean checked = false;
			bis = new BufferedInputStream(inputStream);
			bis.mark(0);
			int read = bis.read(first3Bytes, 0, 3);
			if (read == -1)
				return charset;
			if (first3Bytes[0] == (byte) 0xFF
					&& first3Bytes[1] == (byte) 0xFE) {
				charset = "UTF-16LE";
				checked = true;
			} else if (first3Bytes[0] == (byte) 0xFE
					&& first3Bytes[1] == (byte) 0xFF) {
				charset = "UTF-16BE";
				checked = true;
			} else if (first3Bytes[0] == (byte) 0xEF
					&& first3Bytes[1] == (byte) 0xBB
					&& first3Bytes[2] == (byte) 0xBF) {
				charset = "UTF-8";
				checked = true;
			}
			bis.reset();
			if (!checked) {
				while ((read = bis.read()) != -1) {
					if (read >= 0xF0)
						break;
					if (0x80 <= read && read <= 0xBF) // 单独出现BF以下的，也算是GBK
						break;
					if (0xC0 <= read && read <= 0xDF) {
						read = bis.read();
						if (0x80 <= read && read <= 0xBF) // 双字节 (0xC0 - 0xDF)
							// (0x80
							// - 0xBF),也可能在GB编码内
							continue;
						else
							break;
					} else if (0xE0 <= read && read <= 0xEF) {// 也有可能出错，但是几率较小
						read = bis.read();
						if (0x80 <= read && read <= 0xBF) {
							read = bis.read();
							if (0x80 <= read && read <= 0xBF) {
								charset = "UTF-8";
								break;
							} else
								break;
						} else
							break;
					}
				}
			}
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			if (bis != null) {
				bis.close();
			}
		}
		return charset;
	}
	
	/**
	 * 读取文本
	 * 
	 * @param stream 数据流
	 * @return
	 */
	public static String readText(InputStream inputStream,String encoding) {
		StringBuilder txt=new StringBuilder("");
		try {
			
			InputStreamReader read = new InputStreamReader(inputStream,encoding);//考虑到编码格式
        	BufferedReader bufferedReader = new BufferedReader(read);
        	String lineTxt = null;
        	while((lineTxt = bufferedReader.readLine()) != null){
        		txt.append(lineTxt);
        		txt.append(System.getProperty("line.separator"));
        	}
    		IoUtil.close(inputStream);
		} catch (Exception e) {
			IoUtil.close(inputStream);
			throw new RuntimeException(e);
		}
		return txt.toString();
	}
}
